As mentioned in my previous blog post there is new open-source, lambda compatible, on-premise, language agnostic, server-less compute service called IronFunctions.

While IronFunctions is written in Go. Rust is still very much admired language and it was decided to add support for it in the fn tool.

So now you can use the fn tool to create and publish functions written in rust.

Using rust with functions

The easiest way to create a iron function in rust is via cargo and fn.


First create an empty rust project as follows:

$ cargo init --name func --bin

Make sure the project name is func and is of type bin. Now just edit your code, a good example is the following "Hello" example:

use std::io;  
use std::io::Read;

fn main() {  
    let mut buffer = String::new();
    let stdin = io::stdin();
    if stdin.lock().read_to_string(&mut buffer).is_ok() {
        println!("Hello {}", buffer.trim());

You can find this example code in the repo.

Once done you can create an iron function.

Creating a function

$ fn init --runtime=rust <username>/<funcname>

in my case its fn init --runtime=rust seiflotfy/rustyfunc, which will create the func.yaml file required by functions.

Building the function

$ fn build

Will create a docker image <username>/<funcname> (again in my case seiflotfy/rustyfunc).


You can run this locally without pushing it to functions yet by running:

$ echo Jon Snow | fn run
Hello Jon Snow  


In the directory of your rust code do the following:

$ fn publish -v -f -d ./

This will publish you code to your functions service.

Running it

Now to call it on the functions service:

$ echo Jon Snow | fn call seiflotfy rustyfunc 

which is the equivalent of:

$ curl -X POST -d 'Jon Snow' http://localhost:8080/r/seiflotfy/rustyfunc


In the next post I will be writing a more computation intensive rust function to test/benchmark IronFunctions, so stay tune :D